Development of Gastrointestinal Symptoms in Patients With Anorexia Nervosa and Bulimia Nervosa During Weight Rehabilitation Over Time, Depending on the Nutritional Strategy

Not yet recruiting

• Conditions: Anorexia Nervosa; Bulimia Nervosa

• Registration Number: NCT07112014
• Lead Sponsor: University Hospital Tuebingen

Brief Summary

This prospective observational study investigates the development of gastrointestinal (GI) symptoms in patients with anorexia nervosa (AN) and bulimia nervosa (BN) during multi-week inpatient weight rehabilitation. The study explores how the predominant nutritional strategy-flexitarian, vegetarian, or vegan-relates to changes in GI symptoms over the course of treatment. In addition to diet, the study examines how weight gain and other clinical, psychological, and demographic factors influence the trajectory of GI symptoms. Patients complete weekly questionnaires assessing GI symptoms as part of routine care at the Eating Disorder Center of the Klinik Lüneburger Heide, Germany. Further data are drawn from standard clinical assessments, including body weight, body composition, and psychometric instruments. The primary outcome is the change in GI symptom severity (measured via the GSRS score) from admission to discharge, analyzed in relation to dietary pattern and weight development. Secondary analyses will explore symptom progression over time, group differences between AN and BN, and predictors of GI symptom improvement, including dietary intake, baseline psychological status, symptom change, weight trajectory, and treatment duration. The outcomes will be analyzed separately for AN and BN. The study aims to recruit approximately 150 patients with AN and 35-40 with BN. Inclusion requires a diagnosis of AN (any subtype) or BN, age over 12 years, clinical stability, and the ability to provide informed consent. The findings aim to inform evidence-based dietary recommendations for individuals with eating disorders who experience significant GI symptoms during nutritional rehabilitation.

Detailed Description

This prospective observational study investigates the development of gastrointestinal (GI) symptoms in patients with anorexia nervosa (AN) and bulimia nervosa (BN) during multi-week inpatient weight rehabilitation. The study explores how the predominant nutritional strategy-flexitarian, vegetarian, or vegan-relates to changes in GI symptoms over the course of treatment. In addition to diet, the study examines how weight gain and other clinical, psychological, and demographic factors influence the trajectory of GI symptoms. Patients complete weekly questionnaires assessing GI symptoms as part of routine care at the Eating Disorder Center of the Klinik Lüneburger Heide, Germany. Further data are drawn from standard clinical assessments, including body weight, body composition, and psychometric instruments. The primary outcome is the change in GI symptom severity (measured via the GSRS score) from admission to discharge, analyzed in relation to dietary pattern and weight development. Secondary analyses will explore symptom progression over time, group differences between AN and BN, and predictors of GI symptom improvement, including dietary intake, baseline psychological status, symptom change, weight trajectory, and treatment duration. The study aims to recruit approximately 150 patients with AN and 35-40 with BN. Inclusion requires a diagnosis of AN (any subtype) or BN, age over 12 years, clinical stability, and the ability to provide informed consent. The findings aim to inform evidence-based dietary recommendations for individuals with eating disorders who experience significant GI symptoms during nutritional rehabilitation.

Study Timeline

• Status Verified: 2025-07
• Study First Submitted: 2025-07-15
• Study First Submitted QC: 2025-08-07
• Last Update Submitted: 2025-08-07
• Study First Posted: 2025-08-08
• Last Update Posted: 2025-08-08
• Study Start: 2025-08-25
• Primary Completion: 2027-07-31
• Study Completion: 2027-12-31

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 185

Inclusion Criteria

• patients diagnosed with anorexia nervosa (all subtypes)
• patients diagnosed bulimia nervosa

Exclusion Criteria

• patients that are medically unable to fill out a short questionnaire on a weekly base.

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Gastrointestinal Symptoms	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	Score of the Gastrointestinal Symptom Rating Scale assessed upon admission and discharge (two time points), in relation to the predominant dietary pattern (\>80% during the rehabilitation phase), defined as flexitarian, vegetarian, or vegan and body weight development. The Gastrointestinal Symptom Rating Scale is a validated questionnaire : Svedlund J, Sjödin I, Dotevall G. GSRS--a clinical rating scale for gastrointestinal symptoms in patients with irritable bowel syndrome and peptic ulcer disease. Dig Dis Sci. (1988) 33(2):129-34. doi: 10.1007/BF01535722. The primary outcome is analyzed seperately for patients with anorexia nervosa and bulimia nervosa.

Secondary Outcome Measures

Name	Time	Method
Gastrointestinal Symptoms in the Timecourse	Data are continuously collected from admission to discharge. Extraction occurs on the first three days of admission, weekly during the stay (on Mondays or Tuesdays, covering the preceding week), and on the final three days of discharge.	The Gastrointestinal Symptom Rating Scale is assessed weekly during inpatient treament.
Dietary intake	Data are continuously collected throughout the inpatient stay. Extraction takes place on the day of admission, weekly during the stay (on Mondays or Tuesdays, reflecting the data of the preceding week), and on the day of discharge.	Dietary intake is closely monitored from the beginning to the end of the inpatients stay. The data of the plans will be summarized weekly, containing information on the intake of macro- and micronutrients, fibre, energy intake and food groups. The outcome is analyzed seperately for patients with anorexia nervosa and bulimia nervosa.
Body weight	Data are continuously collected from admission to discharge. Extraction occurs the second day in the morning after admission, weekly during the stay (on Mondays or Tuesdays), and at the day of discharge	Body weight in kg is measured in underwear in the morning before breakfast using a calibrated scale in order to calculate the Body mass index or body mass index z-score. The outcome is analyzed seperately for patients with anorexia nervosa and bulimia nervosa.
Body height	Body weight is measured within the first two days after admission and again within the final two days prior to discharge. For inpatient stays exceeding three months, weight measurements are repeated at three-month intervals.	Body height in cm is measured using a standardized stadiometer to calculate the body mass index or the body mass index z-score. The outcome is analyzed seperately for patients with anorexia nervosa and bulimia nervosa.
Body composition	Body composition is measured within the first two days after admission and again within the final two days prior to discharge. The outcome is analyzed seperately for patients with anorexia nervosa and bulimia nervosa.	Body composition is measured with bioelectrical impedance
Eating Disorder Inventory-2 (EDI-2)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	Eating Disorder Inventory-2 (EDI-2): A 91-item self-report questionnaire assessing psychological and behavioral traits related to eating disorders across 11 subscales. Each item is scored from 0 to 2; total scores range from 0 to 182, with higher scores indicating worse outcomes (greater symptom severity. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Three Factor Eating Questionnaire (TFEQ)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a self-report measure of eating behavior with 51 items across three subscales: Cognitive Restraint, Disinhibition, and Hunger. Items are primarily dichotomous (yes/no), with some Likert-scale items. Subscale scores vary in range, and the total score ranges from 0 to 51, with higher scores indicating worse outcomes (e.g., more disinhibited eating, greater hunger, or excessive restraint). Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Symptom-Checkliste (SCL-90-R)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	Symptom-Checklist-90-Revised (SCL-90-R): A 90-item self-report questionnaire assessing general psychological distress across 9 symptom dimensions (e.g., depression, anxiety, somatization) and 3 global indices. Each item is rated from 0 (not at all) to 4 (extremely). Total scores range from 0 to 360, with higher scores indicating worse psychological symptom severity. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Beck-Depressions-Inventar Revision (BDI-II)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a 21-item self-report questionnaire assessing the severity of depressive symptoms over the past two weeks. Each item is rated on a scale from 0 to 3. Total scores range from 0 to 63, with higher scores indicating worse depressive symptom severity. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Obsessive Compulsive Inventory - Revised (OCI-R)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is an 18-item self-report questionnaire measuring the severity of obsessive-compulsive symptoms across 6 subscales (e.g., washing, checking, hoarding). Each item is rated from 0 (not at all) to 4 (extremely). Total scores range from 0 to 72, with higher scores indicating worse obsessive-compulsive symptom severity. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Generalizied Anxiety Disorder Scale-7 (GAD-7)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a 7-item self-report questionnaire assessing symptoms of generalized anxiety over the past two weeks. Each item is rated from 0 (not at all) to 3 (nearly every day). Total scores range from 0 to 21, with higher scores indicating worse anxiety symptom severity. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Wender Utah Rating Scale (WURS-K)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a 25-item self-report questionnaire assessing retrospective childhood symptoms of ADHD in adults. Each item is rated from 0 (not at all or never) to 4 (very much or very often). Total scores range from 0 to 100, with higher scores indicating greater severity of ADHD-related childhood symptoms. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Subthreshold Autism Trait Questionnaire (SATQ)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a 24-item self-report questionnaire measuring the presence of subclinical autistic traits in adults. Each item is rated from 0 (strongly disagree) to 3 (strongly agree). Total scores range from 0 to 72, with higher scores indicating more pronounced subthreshold autistic traits.Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Frost Multidi-mensional Perfectionism Scale (FMPS)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a 35-item self-report questionnaire assessing perfectionism across multiple dimensions, including concern over mistakes, personal standards, and parental expectations. Each item is rated from 1 (strongly disagree) to 5 (strongly agree). Total scores range from 35 to 175, with higher scores indicating greater levels of perfectionism. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Perceived Stress Questionnaire (PSQ)	Data are collected within the first three days after admission and during the final three days before discharge (two time points).	This is a self-report instrument assessing subjective experiences of stress over the past weeks. The standard version includes 30 items, each rated on a scale from 1 (almost never) to 4 (usually). Total scores range from 30 to 120, with higher scores indicating greater perceived stress. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Age	This is assessed upon admission.	Age is assessed by documenting the birth date (day, months, year) from the health insurance card.
Complete Blood Count (CBC) with Differential	Data will be analyzed from samples collected within the first 3 days after hospital admission, weekly throughout the inpatient stay (on or around Day 7, Day 14, etc.), and within the final 3 days prior to discharge.	Complete Blood Count (CBC) with Differential: A standard laboratory test used to assess general health and detect hematological abnormalities. Measures include red blood cells, white blood cells, hemoglobin, hematocrit, platelets, and a differential count of white blood cell subtypes (neutrophils, lymphocytes, monocytes, eosinophils, basophils). Results outside reference ranges may indicate infection, anemia, inflammation, or immune response abnormalities. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Key electrolyte panel for fluid balance, neuromuscular function, and metabolic regulation	Data will be analyzed from samples collected within the first 3 days after hospital admission, weekly throughout the inpatient stay (on or around Day 7, Day 14, etc.), and within the final 3 days prior to discharge.	A standard blood chemistry panel measuring key electrolytes involved in fluid balance, neuromuscular function, and metabolic regulation.; Sodium (Na⁺): typically 135-145 mmol/L; Potassium (K⁺): typically 3.5-5.0 mmol/L; Chloride (Cl-): typically 98-107 mmol/L; Magnesium (Mg²⁺): typically 0.7-1.0 mmol/L; Phosphate (PO₄³-): typically 0.8-1.5 mmol/L Abnormal values may indicate renal dysfunction, metabolic imbalance, or effects of medications. Higher or lower levels indicate worse physiological regulation depending on the parameter. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Liver Function Panel	Data will be analyzed from samples collected within the first 3 days after hospital admission, weekly throughout the inpatient stay (on or around Day 7, Day 14, etc.), and within the final 3 days prior to discharge.	This Liver Function Panel (ALT, AST, GGT, ALP, Bilirubin, Albumin, INR) is a comprehensive blood test panel assessing hepatocellular injury and liver synthetic function.; Alanine aminotransferase (ALT): \< 50 U/L; Aspartate aminotransferase (AST): \< 50 U/L; Gamma-glutamyl transferase (GGT): \< 60 U/L; Alkaline phosphatase (ALP): 35-125 U/L; Total Bilirubin: 0.3-1.2 mg/dL; Albumin: 3.5-5.0 g/dL; International Normalized Ratio (INR): 0.9-1.2 Elevated enzyme levels may indicate hepatocellular injury or cholestasis, while changes in bilirubin, albumin, or INR reflect impaired liver function. Deviations from normal values indicate worsening liver status, depending on the parameter. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Renal Function Panel	Data will be analyzed from samples collected within the first 3 days after hospital admission, weekly throughout the inpatient stay (on or around Day 7, Day 14, etc.), and within the final 3 days prior to discharge.	This Renal Function Panel (Creatinine, Urea/BUN, eGFR) is a standard blood test panel assessing kidney function and glomerular filtration.; Serum Creatinine: typically 0.6-1.3 mg/dL; Blood Urea Nitrogen (BUN)/Urea: typically 7-20 mg/dL (or 2.5-7.1 mmol/L); Estimated Glomerular Filtration Rate (eGFR): \> 90 mL/min/1.73 m² (normal) Abnormal values may indicate impaired renal function, dehydration, or nephrotoxic effects. Higher creatinine or BUN and lower eGFR indicate worse kidney function. Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.
Medication Use	Data will be analyzed from samples collected within the first 3 days after hospital admission, weekly throughout the inpatient stay (on or around Day 7, Day 14, etc.), and within the final 3 days prior to discharge.	Self-reported and/or medically verified use of prescribed or over-the-counter medications during the study period, with a focus on agents affecting gastrointestinal physiology. Values are recorded categorically (e.g., no medication, antidepressants, antipsychotics, anxiolytics, GI-active drugs, other). Data are analyzed separately for patients with anorexia nervosa and bulimia nervosa.

Trial Locations

Locations (1)

Klinik Lüneburger Heide; 🇩🇪 Bad Bevensen, Germany